Ashesh Mehta

Ashesh Mehta, MD PhD

The clinical circumstance of invasive electrode implantation for the purposes of mapping function and pathology in patients with intractable focal epilepsy provides an unparalleled access to human brain physiology. The comprehensive epilepsy center at Northwell Health performs approximately 50-75 epilepsy surgery procedures annually involving implantation of electrodes for seizure monitoring and neurostimulation, extraoperative functional electrical stimulation mapping and therapeutic removal of epileptic brain tissue by surgical resection or ablation. Our lab uses this as an opportunity to study properties of brain networks, cognitive neurophysiology, validation of noninvasive neuroimaging with invasive electrophysiology and the effects of cortical stimulation on cognition and behavior. In this capacity, our lab is uniquely situated with the access to carry out research involving some of the most direct observations of in vivo human brain physiology.

One focus of the lab involves intraindividual, multimodal comparisons of networks using noninvasive intrinsic functional connectivity analysis applied to MRI and invasive electrocorticography. We have shown consistent intraindividual correspondence of network measures. Furthermore, we have developed databases of patients who have undergone invasive electrode monitoring with multiple intraindividual measures of brain connectivity including DTI, resting fMRI, electrocorticography, and cortico-cortical evoked potentials. We have also collected and archived data with regard to localization of functional areas using electrical stimulation mapping and task-related electrocorticography/fMRI as well as clinical measures including localization of the seizure onset zones, extent of resection and surgical outcome. We believe that these datasets will not only provide a more detailed understanding of brain networks, but because epilepsy is a network disease, these studies may ultimately improve epilepsy surgery outcome.

Another area of interest involves the neurophysiological basis of perception, cognition and action. With such direct access to human electrophysiology, we have studied the neurophysiological basis of a number of cognitive phenomena including language, visual object identification, attention, memory and motor planning. Furthermore, with direct cortical stimulation, we have begun to unravel how neuromodulation may be used to improve these various aspects of cognitive function.